This story is about a young man named Radius, the son of Sir Cumference and Lady Di of Ameter, and the quest he must pursue to become a knight. He uses his family's prized possession, a medallion in the shape of a circle, to help him on his quest. He uses geometry and his knowledge of different kinds of angles to help him in his adventures.

Professional Commentary: Using inductive reasoning, students devise procedures for using a protractor to measure the number of degrees in an angle. Students make estimates of the measurement of various angles created with angle wheels....

Professional Commentary: Students use a carpenter's square and protractor to measure the sides and angles of several right triangles. To confirm their measurements, they then compute the size of selected sides and angles using (a) the Pythagorean Theorem and (b) trigonometric ratios....

Professional Commentary: Paper Pool is played with an imaginary ball being hit from the lower left-hand corner of a rectangular grid (pool table) at a 45&#176 angle. A ball hit at this angle will bounce off the side rails of the table at a 45&#176 angle and will traverse the diagonals of the squares in the grid....

Professional Commentary: Have students think of questions to ask about the following situation: Draw on squared paper or build with snap cubes a rectangular pool table. Trace out the path of a ball until it hits a corner....

Benchmarks (5-7)C. Identify appropriate tools and apply appropriate techniques for measuring angles, perimeter or circumference and area of triangles, quadrilaterals, circles and composite shapes, and surface area and volume of prisms and cylinders.

Grade Level Indicators (5)7. Use benchmark angles (e.g.; 45°, 90°, 120°) to estimate the measure
of angles, and use a tool to measure and draw angles.

Benchmarks (5-7)D. Identify, describe and classify types of line pairs, angles, two-dimensional figures and three-dimensional objects using their properties.

Grade Level Indicators (3)2. Identify and describe the relative size of angles with respect to right angles as follows:
a. Use physical models, like straws, to make different sized angles by opening and closing the sides, not by changing the side lengths.
b. Identify, classify and draw right, acute, obtuse and straight angles.